1. Field of the Invention
The present general inventive concept relates to an image forming apparatus, and more particularly, to a belt assembly of a color image forming apparatus using an intermediate transfer belt.
2. Description of the Related Art
In general, conventional color image forming apparatuses have a belt assembly to develop images using a series of developers of different colors.
Belt assemblies are designed to rotate continuously so that conveyed print material may receive images of a variety of colors from one or more photoconductive media. If there is a single photoconductive medium, the number of times the belt assembly rotates is equal to the number of different colors required. If the number of the photoconductive media is equal to the number of different colors, the print material conveyed by the belt assembly can receive an entire color image with a single rotation.
Usually, the belt assembly includes a frame, a driving roller, an idle roller, a first transfer roller, and an intermediate transfer belt.
The driving roller, the idle roller, the first transfer roller, and the intermediate transfer belt are mounted rotationally on the frame.
The driving roller receives power to rotate the intermediate transfer belt. The idle roller is supported by elastic members having the same elastic coefficient, and together with the driving roller provides the intermediate transfer belt with a fixed level of tension.
First and second guiding members are installed on the static side of the driving roller and the idle roller. The first and second guiding members have a guiding groove which houses a guiding rail formed on the intermediate transfer belt to prevent the intermediate transfer belt from meandering. The intermediate transfer belt can thus perform continuous rotation without meandering with the guiding rail inserted in the guiding groove.
The first transfer roller is disposed between the driving roller and the idle roller so that the photoconductive medium and the intermediate transfer belt form a transfer nip.
The intermediate transfer belt is rotated and supported by the driving roller and the idle roller, and receives an image from the photoconductive medium. The intermediate transfer belt includes the guiding rail to eliminate meandering as described above, and a sensor hole which senses the location of the intermediate transfer belt.
Generally, the intermediate transfer belt with the sensor hole is attached with a reinforcing tape of equal width to prevent the intermediate transfer belt from being damaged due to cracks occurring around the sensor hole.
The reinforcing tape has consistent thickness, so a non-contact space is created between the reinforcing tape and the driving roller at the contact area between the driving roller and the reinforcing tape which is not created at the contact area between the driving roller and the guiding rail since that contact area does not include the reinforcing tape.
If the intermediate transfer belt has an uneven surface and rotates rapidly, the contact area of the intermediate transfer belt between the driving roller and the reinforcing tape is partially deformed, so waves or troughs occur. The waves or troughs deform the transfer nips formed on the photoconductive medium and the first transfer roller, so that the flatness of the transfer nips is damaged and image errors such as irregular horizontal bands occur.